WordNet (r) 3.0 (2006):

volatile storage
    n 1: computer storage that is erased when the power is turned
         off [ant: non-volatile storage, nonvolatile storage]

The Free On-line Dictionary of Computing (30 December 2018):

non-volatile storage
non-volatile
non-volatile memory
persistent memory
volatile memory
volatile storage

    (NVS, persistent storage, memory) A term describing
   a storage device whose contents are preserved when its power
   is off.  Storage using magnetic media (e.g. magnetic disks,
   magnetic tape or bubble memory) is normally non-volatile
   by nature whereas semiconductor memories (static RAM and
   especially dynamic RAM) are normally volatile but can be
   made into non-volatile storage by having a (rechargable)
   battery permanently connected.

   Dynamic RAM is particularly volatile since it looses its
   data, even if the power is still on, unless it is refreshed.
   An acoustic delay line is a (very old) example of a volatile
   storage device.

   Other examples of non-volatile storage are EEPROM, CD-ROM,
   paper tape and punched cards.

   (2000-05-22)